1 files changed, 106 insertions, 0 deletions
diff --git a/libtomcrypt/src/encauth/ocb3/ocb3_add_aad.c b/libtomcrypt/src/encauth/ocb3/ocb3_add_aad.c
new file mode 100644
index 0000000..70e3211
--- /dev/null
+++ b/libtomcrypt/src/encauth/ocb3/ocb3_add_aad.c
@@ -0,0 +1,106 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+/**
+   @file ocb3_add_aad.c
+   OCB implementation, add AAD data, by Karel Miko
+*/
+#include "tomcrypt.h"
+
+#ifdef LTC_OCB3_MODE
+
+/**
+   Add one block of AAD data (internal function)
+   @param ocb        The OCB state
+   @param aad_block  [in] AAD data (block_len size)
+   @return CRYPT_OK if successful
+*/
+static int _ocb3_int_aad_add_block(ocb3_state *ocb, const unsigned char *aad_block)
+{
+   unsigned char tmp[MAXBLOCKSIZE];
+   int err;
+
+   /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
+   ocb3_int_xor_blocks(ocb->aOffset_current, ocb->aOffset_current, ocb->L_[ocb3_int_ntz(ocb->ablock_index)], ocb->block_len);
+
+   /* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
+   ocb3_int_xor_blocks(tmp, aad_block, ocb->aOffset_current, ocb->block_len);
+   if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) {
+     return err;
+   }
+   ocb3_int_xor_blocks(ocb->aSum_current, ocb->aSum_current, tmp, ocb->block_len);
+
+   ocb->ablock_index++;
+
+   return CRYPT_OK;
+}
+
+/**
+   Add AAD - additional associated data
+   @param ocb       The OCB state
+   @param aad       The AAD data
+   @param aadlen    The size of AAD data (octets)
+   @return CRYPT_OK if successful
+*/
+int ocb3_add_aad(ocb3_state *ocb, const unsigned char *aad, unsigned long aadlen)
+{
+   int err, x, full_blocks, full_blocks_len, last_block_len;
+   unsigned char *data;
+   unsigned long datalen, l;
+
+   LTC_ARGCHK(ocb != NULL);
+   if (aadlen == 0) return CRYPT_OK;
+   LTC_ARGCHK(aad != NULL);
+
+   if (ocb->adata_buffer_bytes > 0) {
+     l = ocb->block_len - ocb->adata_buffer_bytes;
+     if (l > aadlen) l = aadlen;
+     XMEMCPY(ocb->adata_buffer+ocb->adata_buffer_bytes, aad, l);
+     ocb->adata_buffer_bytes += l;
+
+     if (ocb->adata_buffer_bytes == ocb->block_len) {
+       if ((err = _ocb3_int_aad_add_block(ocb, ocb->adata_buffer)) != CRYPT_OK) {
+         return err;
+       }
+       ocb->adata_buffer_bytes = 0;
+     }
+
+     data = (unsigned char *)aad + l;
+     datalen = aadlen - l;
+   }
+   else {
+     data = (unsigned char *)aad;
+     datalen = aadlen;
+   }
+
+   if (datalen == 0) return CRYPT_OK;
+
+   full_blocks = datalen/ocb->block_len;
+   full_blocks_len = full_blocks * ocb->block_len;
+   last_block_len = datalen - full_blocks_len;
+
+   for (x=0; x<full_blocks; x++) {
+     if ((err = _ocb3_int_aad_add_block(ocb, data+x*ocb->block_len)) != CRYPT_OK) {
+       return err;
+     }
+   }
+
+   if (last_block_len>0) {
+     XMEMCPY(ocb->adata_buffer, data+full_blocks_len, last_block_len);
+     ocb->adata_buffer_bytes = last_block_len;
+   }
+
+   return CRYPT_OK;
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */